re PR c++/59916 (constructors and destructors can cause "control reaches end of…

re PR c++/59916 (constructors and destructors can cause "control reaches end of non-void function" warnings with -Os)

	PR c++/59916
	* optimize.c (maybe_thunk_body): Build a RETURN_EXPR for
	cdtor_returns_this case.

From-SVN: r207271

gcc/cp/ChangeLog

 2014-01-29  Jason Merrill  <jason@redhat.com>
 
+	PR c++/59916
+	* optimize.c (maybe_thunk_body): Build a RETURN_EXPR for
+	cdtor_returns_this case.
+
 	PR c++/59315
 	* decl.c (cxx_maybe_build_cleanup): Call mark_used.
 

gcc/cp/optimize.c

@@ -405,8 +405,8 @@ maybe_thunk_body (tree fn, bool force)
 	      clone_result = DECL_RESULT (clone);
 	      modify = build2 (MODIFY_EXPR, TREE_TYPE (clone_result),
 			       clone_result, call);
+	      modify = build1 (RETURN_EXPR, void_type_node, modify);
 	      add_stmt (modify);
-	      BLOCK_VARS (block) = clone_result;
 	    }
 	  else
 	    {

gcc/testsuite/g++.dg/warn/Wreturn-type-10.C

+// PR c++/59916
+// { dg-options "-Os -Wreturn-type" }
+
+class A {};
+
+struct B : virtual public A
+{
+  B();
+  virtual ~B();
+};
+
+B::B() {}
+B::~B() {}